Method for polymerizing fatty acids

ABSTRACT

A METHOD FOR POLYMERIZATION OF UNSATURATED FATTY ACIDS IS PROVIDED. IN THE METHOD, POLYMERIZATION OF UNSATURATED FATTY ACIDS IS EFFECTED BY HEATING UNSATURATED FATTY ACIDS IN THE PRESENCE OF A PARTICULAR NEUTRAL CLAY CATALYST. THE USUAL TEMPERATURE RANGE EMBRACED IS FROM ABOUT 225*C. TO ABOUT 270*C. FOR A PERIOD OF ABOUT ONE HOUR TO ABOUT FIVE HOURS AT A PRESSURE OF FROM ABOUT 90 P.S.I.G. TO ABOUT 160 P.S.I.G. MOISTURE IS USUALLY PRESENT IN THE REACTION MIXTURE IN AN AMOUNT OF FROM ABOUT 2 TO ABOUT 5 PERCENT BY WEIGHT OF THE REACTION MIXTURE.

United States Patent 3,732,263 METHOD FOR POLYMERIZING FATTY ACIDS Lawrence U. Berman, Skokie, Ill., assignor to Kraftco Corporation, New York, N.Y. N0 Drawing. Filed Sept. 16, 1970, Ser. No. 72,845 Int. Cl. C09f 7/06; C11c 3/00 US. Cl. 260-407 4 Claims ABSTRACT OF THE DISCLOSURE The present invention relates to polymerization of unsaturated fatty acids to provide a product having a high level of dimerized fatty acids. In particular, the invention relates to the use of a particular neutral clay as a catalyst to provide a high yield of polymerized fatty acids.

Polymerized fatty acids, particularly dimerized fatty acids, are used for the preparation of polyamide resins and other resin products. It is known to employ various clay catalysts for the purpose of polymerizing fatty acids to provide polymerized fatty acids having a content of dimerized fatty acids. Both acid and alkaline clay catalysts have been used in the art. However, the known alkaline and acid catalysts which have been taught by the prior art have not been completely satisfactory.

For example, in the polymerization of fatty acids, it is desirable to use as low a level of clay catalyst as possible so that a subsequent filtration step used to separate the polymerized fatty acids from the catalyst may be practiced as effectively and economically as possible. It is also desirable to provide polymerized fatty acids having a high ratio of dimerized fatty acids to trimerized fatty acids and at as high a yield as possible. It is also desirable to provide a product with a high acid value. It is further desirable not to effect saponification of the fatty acids during the reaction by forming soaps. The presence of soaps is detrimental to the product.

The prior art has not succeeded in supplying a clay catalyst for use in the polymerization of fatty acids which fully meets all of the desired requirements indicated above. For example, in U.S. Pat. No. 3,157,681 to Fischer, a particular clay catalyst is described which effects polymerization of fatty acid mixtures in high yields. However, a high level of catalyst is required, and the particular catalyst taught by the Fischer patent is not completely satisfactory in that such high catalyst levels must be used.

The use of alkaline catalysts and alkaline materials during the polymerization reaction is taught in US. Pat. No. 2,955,121 to Myers et al. However, saponification occurs in the use of alkaline materials and this is not usually desirable. The use of acid clay catalysts are taught in US. Pat. No. 2,793,220 to Barrett et al. However, use of the acid clay catalysts of the Barrett et al. patent have not generally provided a high polymerization yield. As indicated, it is desirable to provide a catalyst which is capable of providing higher yields.

It is therefore a principal object of the present invention to provide a particular neutral clay catalyst for use 3,732,263 Patented May 8, 1973 in preparing a product having a high content of dimerized fatty acids. It is also an object of the present invention to provide an improved process for the polymerization of unsaturated fatty acids. It is a further object of the present invention to provide a particular neutral clay catalyst for use in the manufacture of polymerized fatty acids. A more particular object is the provision of a process which provides a high yield of dimerized fatty acids and a high ratio of dimerized fatty acids to trimerized fatty acids. A still further particular object is the provision of a process which provides high yield of dimerized fatty acids with minimum saponification.

Generally, in a process including various features of the invention, polymerization of unsaturated fatty acids is effected by heating an individual unsaturated fatty acid, or mixture of unsaturated fatty acids, in the presence of a particular neutral clay catalyst, hereinafter described in detail. The usual temperature range employed is from about 225 C. to about 275 C. for a period of fromabout one hour at about five hours. The polymerization reaction is usually carried out under pressure of from about p.s.i.g. to about p.s.i.g., and moisture is usually present in the reaction mixture in an amount of from about 2 to about 5 percent by weight of the reaction mixture.

After the polymerization reaction, the product is cooled and filtered to remove the clay catalyst. Unreacted monomeric material is then removed by distillation or other means, leaving a polymeric fatty acid product having a high content of dimerized fatty acids, referred to as dimers, unreacted fatty acids, called monomers, and more highly polymerized fatty acids known as trimers. The polymeric fatty acid product may be further treated by bleaching and hydrogenation processes in accordance with known methods, if desired.

As previously indicated, it is generally known from the literature that various clays may be used as catalysts in the polymerization of fatty acids. It is also known that similar clays varying little in composition, vary greatly in the type and extent of activity that are associated with the clay during the polymerization reaction. Accordingly, it has not been possible to predict the ability of a clay to catalyze fatty acid polymerization reactions. The exact characteristics of any particular clay which account for its behavior as a polymerization catalyst is not understood, and the effectiveness of a clay for the purpose of effecting polymerization of fatty acids is wholly unpredictable.

Accordingly, it is totally unexpected that the use of a particular neutral clay catalyst as taught by the present invention is sufiicient to overcome many of the problems associated with the preparation of polymerized fatty acids. This discovery is entirely unexpected, surprising and fortuitous because of the lack of predictability of the catalytic activity of particular clays.

Higher unsaturated fatty acids having from 8 to 22 carbon atoms may be employed in the process of the present invention. The process is particularly adapted to the polymerization of fatty acids derived from common raw materials ordinarily used as a source to provide unsaturated fatty acids. In this connection, soy fatty acids derived from soy bean oil, linseed oil, cottonseed oil, safflower oil and fish oils, tallow fatty acids and tall oil fatty acids may be used. Saturated fatty acids usually occur in nature with unsaturated fatty acids. The saturated acids do not polymerize in the process of the invention; however, separation of the saturated from the unsaturated fatty acids before polymerization is not necessary, and the polymerization may be carried out in the presence of saturated fatty acids which remain unreacted during the process. After polymerization, the unreacted material, including saturated fatty acids and any unreacted, unsaturated fatty acids may, if desired, be removed by distillation or other means.

The clay catalyst used in the method of the invention is a neutral, bentonite, crystalline clay material having a neutral pH of between about 6.5 and 7.5. The clay is 4 ferred to use levels of clay catalyst above about two percent.

When used to effect polymerization of tall oil fatty acids, Alabama neutral clay provides yields of polymerized product of from about 55 percent up to about 65 percent mined by American Colloid Company from its mines near by weight of the starting fatty acid weight. The polymer- Leetchatchee, Ala., and is sold under the trade name ized product generally has a dimer content of at least Panther Creek Neutral Clay. This clay has been mined about 70 percent, and may provide a dimer content in and sold for many years for the purpose of bonding said excess of 80 percent. A distilled polymerized product in metal casting and for filtering and decolorizing oils. is obtained with from about 80 to about 97 percent total However, the ability of this clay to function as a superior polymerized fatty acids and with a dimer to trimer weight catalyst in a process for making polymerized fatty acids ratio of from about 4:1 to about 8:1. The polymerized has not been recognized. For ease in reference, the new product has an acid value of from about 180 to about tral c ay of the invention will be sometimes referred to 190 and a saponification value of from about 192 to about hereinafter in the specification and claims as Alabama 198. neutral clay. The following examples illustrate various features of AS P y indicated, it is diificlllt, f ot impossible, the invention, but are intended to in no way limit the to ascertain the catalytic effectiveness of clays on the scope of the invention which is defined in the appended basis of chemical analysis. However, the particular clay clai used in the process of the present invention is fully dis- 2 closed for the purposes of those skilled in the clay art by 0 EXAMPLE I reference to Its trade name and generic type Fatty acids (100 parts) which were obtained from the 4 Smith of the mental clay when analyzed on a dry distillation of tall oil, were charged into a small laborabasls pmvlded the followmg results: tory pressure vessel. The fatty acids comprised 95 per- Ingredient: Wt, percent cent unsaturated acids. Various clay catalysts (4 parts),

Sio2 56:8 to 588 including the neutral clay catalyst of the present inven- Alzoa 185m 203 tion, were then dispersed 1n the fatty acids. Water (2 F6203 50 to parts was then added to the mixture and the pressure F60 05 to vessel was sealed. The mixture in the pressure vessel was Mgo 3.1to3 3 then agitated and heated to and maintained at a temcao 1.4 to perature of 240 C. to 250 C. for a period of four Nazo 0.3 to hours. At the end of this period, the mixture was cooled K20 0.6 to to 120 C. and the water was removed In the form of Tio 0 8 to 0'9. steam with the aid of a slow current of mtrogen. The so 2 0 or less reaction mixture was cooled to 95 C. and was then fil- 4 to 1 tered to remove the clay catalyst. The polymerized fatty 2 acids were separated from the saturated fatty acid and The neutral clay of the invention as provided by the unreacted unsaturated fatty acids by simple overhead dis- American Colloid Company is in the form of a fine powtillation from a glass flask. The monomer, dimer and der of which 100 percent passes 150 mesh screen and 40 trimer content of the polymerized fatty acid product was 90 percent passes a 200 percent mesh screen. determined by thin layer chromatographic analysis. The The full benefits of the use of Alabama neutral clay results with respect to the various clay catalysts used are are obtained when the amount of clay employed in the reported below in Table I.

TABLE 1 Type clay catalyst Ala- Bennett bama. Clark Filtrol Flltrol Super Neutral Palex Impact Neutral Natur 1e 20 Filtrol 40 II 150 Clay t vi iil i i l ie aiefin; 8. 3 3. 2 a. 1 a. 5 3. 2 7. 1 2. 7 5. 8

Reaction results Acid value (A.v.)-..- 187.1 191.5 175 s 181.0 177.1 190.5 176.0 187.4 Weight percent of residue after stripping:

Monomer-.. 5-10 10 10 10-15 10-15 10-15 15-20 5 Dimer 70-75 65-70 65-70 70 -70 70 70 so Trirner 15-20 15-20 15-20 15-20 15-20 15 15 10-15 Dimer to trimer ratio 3.5-4.7 3.2-4.7 3.2-4.7 3.5-4.7 3 2-4.7 4.7 4.7 5. 3-8.0 Yield 49. 0 54.2 60. e0. 0 60.4 42. 7 59. a 57. 7

polymerization reaction is from about one percent to about four percent by weight of the unsaturated fatty acids to be polymerized. Higher levels of clay may also be used, but no improved results are obtained. As previously indicated, the use of higher levels of clay catalyst are desirably avoided to enhance the economics of the process, particularly by increasing etficiency in the filtration step. One of the principal advantages of the present invention is the low level of clay that may be used and still obtain high yields of a polymerized product with a high dimer to trimer ratio. At levels of use of the clay catalyst below about two percent, there is some decline in conversion yield. It is, therefore, preabout 7.5.

2. A process in accordance with claim 1 wherein said References Cited Alabama neutral clay catalyst is present at a level of from UNITED STATES PATENTS about 1 percent to about 4 percent by weight of said fatty acids 2,955,121 10/1960 Myers et a]. i i 260-407 3. A process in accordance with claim 1 wherein said 3,507,390 4/ 1970 Dleckelmann et 260407 heating is at a temperature of from about 225 C. to 5 LEWIS GOTTS p i Examiner about 27 C. for a eriod of fro about one hour to about houm p m D. G. RIVERS, Assistant Examiner 4. A process in accordance with claim 1 wherein water U S CL X R is present during said heating at a level of from about 2 260 97 5 percent to about 5 percent by weight of the reaction 10 mixture. 

